Human NKT Cells Express Granulysin and Exhibit Antimycobacterial Activity

Abstract

Human NKT cells are a unique subset of T cells that express an invariant Vα24 TCR that recognizes the nonclassical Ag-presenting molecule CD1d. Activation of NKT cells is greatly augmented by the marine sponge-derived glycolipid α-galactosylceramide (αGalCer). Because human monocyte-derived cells express CD1d and can harbor the intracellular pathogen Mycobacterium tuberculosis, we asked whether the addition of αGalCer could be used to induce effector functions of NKT cells against infected monocytes, macrophages, and monocyte-derived dendritic cells. NKT cells secreted IFN-γ, proliferated, and exerted lytic activity in response to αGalCer-pulsed monocyte-derived cells. Importantly, αGalCer-activated NKT cells restricted the growth of intracellular M. tuberculosis in a CD1d-dependent manner. NKT cells that exhibited antimycobacterial activity also expressed granulysin, an antimicrobial peptide shown to mediate an antimycobacterial activity through perturbation of the mycobacterial surface. Degranulation of NKT cells resulted in depletion of granulysin and abrogation of antimycobacterial activity. The detection of CD1d in granulomas of tuberculosis patients supports the potential interaction of NKT cells with CD1d-expressing cells at the site of disease activity. These studies provide evidence that αGalCer-activated CD1d-restricted T cells can participate in human host defense against M. tuberculosis infection.

NK-lysin of channel catfish: Gene triplication, sequence variation, and expression analysis

“…In recent years, extensive research has been conducted for the analysis of structure and antimicrobial activities of NK-lysin (Stenger et al, 1998;Ernst et al, 2000;Gansert et al, 2003;Jacobs et al, 2003). NK-lysin genes share sequence similarities to the poreforming proteins of Entamoeba histolytica, termed amoebapores (Leippe, 1995).…”

“…NK-lysin genes share sequence similarities to the poreforming proteins of Entamoeba histolytica, termed amoebapores (Leippe, 1995). They have been reported to have antimicrobial activities against a wide spectrum of microorganisms including bacteria, fungi, protozoa, and parasites (Stenger et al, 1998;Ernst et al, 2000;Gansert et al, 2003;Jacobs et al, 2003), and therefore, have been widely regarded as antimicrobial peptides. In contrast to classical antibiotics, these peptides act by direct physical destabilization of the target cell membrane with a high specificity for bacteria (Schroder-Borm et al, 2003).…”

Mycobacterial Lipopeptides Elicit CD4+ CTLs in Mycobacterium tuberculosis-Infected Humans

“…A total of 2.4 ϫ 10 6 cells/well were seeded in a 24-well plate in the presence of the chloroform methanol extract of M.Tb (M.Tb-CME) or PPD. After 7-10 days, cells were costained for cell surface markers (CD3, CD8, CD4, CXCR-3, CCR5, CCR7, CD45RO) or intracellular molecules (granulysin, perforin, granzyme B) as previously described (34). CFSE low (proliferated) cells were detected by flow cytometry and further analyzed for the expression of additional parameters.…”

Innate Immunity-Based Immunotherapy of Cancer

“…Because of the low contents of agelasphins in the marine sponge, and the difficulty of their scale-up synthesis, the structure of agelasphins was modified, and a novel compound, α-GalCer (also called KRN7000) was synthesized . This glycolipid was shown to bind non-classical MHC molecule CD1d of human and mice (Gansert et al, 2003;Taniguchi & Nakayama, 2000), and activate natural killer T (NKT) cells of both species in vitro and in vivo when it is presented on CD1d molecule Burdin et al, 1998;Kawano et al, 1998;Spada et al, 1998) . To date,-GalCer has been the most extensively studied ligand for CD1d molecules and stimulant for NKT cells.…”